1. ## simple sbs tester

I made some pictures of the idea above, that may show it better

2. Originally Posted by stringtechno

Buy this kind of gauge it should not be more expensive than \$20.
Attachment 155517

.
What kind of gauge is that, a dynamometer, or should it measure distance ?

I would like to build this setup to test the results from my stringway bl-90

update: searched a bit more and I thinks it's called meetklok in dutch and measures distance.

4. Hi MvdZwaan, also Dutch I see.

As you already found out the clock is a normal distance measuring clock , you can buy this in the Netherlands with Hogetex for € 12.

This is one

http://www.hogetex.com/analoge-meetklok-0-10mm-0-01mm.html

The weight should be at least so high that you can measure a reasonable deflection of the stringbed. If you use 2 to 4 kg the deflection will be 1,5 to 3 mm which is perfect.

5. I just performed a small test, old racket strung with tactic TG-80 couple of months ago at 13.0/13.5 kg (just a test then to see how this tension worked out on my stringway).

I used a 6KG weight, and the deflection was 0.85mm.... That would equate to ~7KG/cm2 which seems to be too low...

Now to find out what I did wrong... I used a 4cm spacer ring on the stringbed which perhaps spreads out the weight too much ? (You did mention 4cm in your instructions)

6. With a 2cm diameter washer the deflection was 1.58mm. So that is one of the factors to use in the calculation, and it only weight divided by deflection. Seem perfectly logical to me...

Now to get the right diameter to compare to stringlab2....

Or is your suggestion to only use these measurements to compare to my own results ?

7. My weight is not 6KG but 3 I used an old dumbell with 3 on each side, so thought it was 6 .

So the 1st measurement actually is 3.5KG/cm2 with 4 cm washer. Should I multiply this with the surface area of the washer (12.5664) and thus the SBS is 44KG/cm2 ?

8. ## Kg per cm result

Good Dutch work Mvd Zwaan,

If your test is 0,85 deflection with a force of 3kg your stiffness is 3,53 kg/mm.
This means 35 kg/cm.

The Stringlab measures in kg/cm.

This is the highest value for badminton that I heard of and I think it is much too stiff.
Tennis pro’s use 34 to 37 kg/cm directly after stringing.
I doubt that 35 kg/cm can not offer the right feeling when playing with it in badminton. The shaft is much too flexible to cope with that.

I can send you the list with test results so that you can see at what stiffness values other stringers work.

The diameter of the disc is very important and 4 cm is kind of standard. All Stiffness testers which were on the market use this size including the Stringlab 2.

9. Just measured 3 others rackets,

Yang Yang Sword II1, BG-65, 8.0/8.5KG, strung 22-feb : 164 deflection : 18.2KG/cm
Yonex ArcSaber 11, BG-70Pro, 9.5/10KG, 25-nov : 162 : 18.5KG/cm
Yonex Voltric VT-70, BG-65, 9.5/10KG, strung oct/nov: 128, 23.4KG/cm

So only the ArcSaber with BG-70Pro seems odd (BG-70 has stiffer feel than BG-65, and is less elastic...). It's my main racket, and I have played 3 hours a week with it since stringing it.

10. ## Important for (tournement) players

I think that 15 to 25 kg/cm is the right stiffness for badminton depending on the preference of the player.

One of the main things of testing the stiffness as a player is that he knows his favorite stiffness and also knows when a restring is needed.

This is especially important for tournament players who have to deal with different stringers on every tournament.

11. ## photo's instead of drawings

Up till now we only showed pictures from our 3D drawing system, hereby some pictures showing the use for badminton.

12. ## Videos of the test system

Hereby a video which shows the test of a badminton stringbed and the stiffness of the racquet.

This video shows all the functions of the Stringlab 2 system

Please do not hesitate to come up with any comments that you have.

13. ## New test results

We received stringing information again so we send that to you.

Hereby some remarks concerning the project and the information.
There 19 people involved in the project at the moment in different ways but all are specialized in badminton stringing.

- The test results come from 2 stringers and the information of both is kept together, white and green background. The type of machine that is used is shown at the top of each list in green.
- The results are sorted on stringing tension, so that you can see the stiffness results in relation to the tension for the different strings.

About how to look at the figures.
There may be some misunderstanding about the intention of these test results.

It is not a “stiffness contest”, in which you are doing bad when your stringing results are lower at comparable tensions.

The main object of the test list is that stringers find the relation between tension and SBS with their way of stringing and with their stringing machine.

Meaning;
- If a stringer chooses to string very fast he needs higher tensions to obtain the same stiffness.
- If a stringer uses a machine with bad or no constant pull action, he needs higher tensions to obtain certain SBS results.
- Stringers with electronic machines may need less tension. Many electronic machine overpull the adjusted tension.
- Strings with more remaining elongation need higher tensions to obtain certain SBS results.

Summarized:
There are a lot of ways to reach the right result.

Questions.
The list with stringing results will supply a relation between stringing tensions, strings and stringing results (SBS in kg/cm).

Important relation which we still have to find is the one between playability and stiffness.
When we want to develop a Tension Advisor for badminton we need to know the best SBS for the different types of players.

Another interesting question is:
Does it really make sense to string at tension up to 14 kg?

With a tension of 11,8 kg the stiffness is 32,8 kg/cm, which would mean about 39 kg/cm for 14 kg. This SBS is extremely high even compared to tennis.

It could be that stringers stringing on these tensions go so fast that they have to use these tension to obtain a much lower SBS because they loose more tension than the slower stringers?

I talked to our Dutch agent he told me that the Koreans start to lower the stringing tensions considerably. If you know more about this please let us know.

http://www.stringway-nl.com/pdf/STRI...tension-2 .pdf

If you have any kind of questions please let me know.

14. Originally Posted by stringtechno
Another interesting question is:
Does it really make sense to string at tension up to 14 kg?

With a tension of 11,8 kg the stiffness is 32,8 kg/cm, which would mean about 39 kg/cm for 14 kg. This SBS is extremely high even compared to tennis.

It could be that stringers stringing on these tensions go so fast that they have to use these tension to obtain a much lower SBS because they loose more tension than the slower stringers?

I talked to our Dutch agent he told me that the Koreans start to lower the stringing tensions considerably. If you know more about this please let us know.
This is just not true as at the recent All England one of our members strung for the Victor players and for instance Shin Baek Cheol requested 15KG as well as Lee Dong Keun. Maybe he couldn't tell a male name from a female korean name but even the ladies are still playing with 13KG ...
On a sidenote: Kenichi Tago of Japan plays with 16KG

Here is a list of requested tensions from this recent AE tournament: http://www.badmintoncentral.com/foru...=1#post2211844

15. Thanks for the info demolidor.

I will ask my agent, I think it was about Koreans who play in Europe.

The major and interesting question remains:
- OK so they play with even these high tensions, I know.

What are the arguments?

We have quite some badminton stringers and players in the team, but nobody gives an answer to this question.

OR is it the same as with tennis 15 years ago: They do it because everybody does it.

Seles played with 40 kg in an oversize and Agasi with 36 kg, the SBS must have been 45 kg/cm and higher.

It is always better to translate that into stiffness because that is what the player feels.

The big tennis players play with around 35 kg/cm.

16. When comparing SBS between tennis and badminton, I think one reason why pro badminton players can use such relatively high tensions and SBS is because of the relatively flexier shaft of the badminton racket in comparison to the tennis racket.

Just look at the Korean team for example. Their favourite racket (half the team uses it!) is BS12, which is quite flexible even for most badminton rackets. So in order to compensate for that, they string higher SBS.

17. Originally Posted by stringtechno
Thanks for the info demolidor.

I will ask my agent, I think it was about Koreans who play in Europe.

The major and interesting question remains:
- OK so they play with even these high tensions, I know.

What are the arguments?

We have quite some badminton stringers and players in the team, but nobody gives an answer to this question.

OR is it the same as with tennis 15 years ago: They do it because everybody does it.

Seles played with 40 kg in an oversize and Agasi with 36 kg, the SBS must have been 45 kg/cm and higher.

It is always better to translate that into stiffness because that is what the player feels.

The big tennis players play with around 35 kg/cm.
Higher tension generally means better feeling and accuracy, but also more energy transfer to the shuttle. Maximum power increases with tension while lower tensions help attain more power with less energy but with a lower power "cap".

As athletes (and rackets) become stronger and stronger, they are able to increase their tension in order to raise that power cap in a comfortable way (aka not needing all their energy to clear). The popular test to determine an adequate tension is to clear baseline to baseline. If you can do it without much effort (comfortably), you can increase your tension by 1 lb. When it starts taking a little too much effort, you know you just crossed your ideal tension and should decrease by 0.5-1 lb for the next stringjob and keep it there.

While it may be tempting to compare badminton to tennis, the swings are very different and the momentum created by the rackets too (not to mention the difference in projectiles). Badminton players are able to generate much bigger and more powerful swings because a good majority of the shots are overhead. Also, pro tennis players put all their power in 90% of their strokes (which demands a lot of energy) while badminton players only put all their power when they smash (and even then, sometimes they don't).

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